The present invention relates to titanium carbonitride ceramics having high density, high hardness and high strength, wherein such ceramics are used for materials for cutting tools or wear-resistant machine parts.
Tungsten carbide has been mainly used for cutting tool materials, in spit but since tungsten raw materials have been insufficient in recent years. Therefore, sintered titanium carbo-nitride bodies or titanium diboride bodies have begun to attract attention.
Titanium carbo-nitride exists as a solid solution of TiN and TiC where, the proportion of carbon and nitrogen in the solid solution is easily distributed. It is confirmed by X-ray diffraction that titanium carbo-nitride is a completely different material from titanium carbide and titanium nitride, and the material properties such as hardness and toughness or the sinterability are also different. Titanium carbo-nitride has a high melting point, high hardness, high toughness and oxidation resistance, and is used as material for cutting tools or wear-resistant machine parts. A sintered body of pure titanium carbo-nitride is rarely used for the above-mentioned purposes because the sintered body has low breaking strength and is brittle.
Composite ceramics of metal boride and titanium carbo-nitride have been already developed by the inventors of the present invention, and are already well-known in Japanese Patent Publication No. 59-18349. Therefore, the present invention is a further development.